Among aircraft maneuvering systems, in the case of an electrical maneuvering system generally referred to as a fly-by-wire (hereinafter referred to as “FBW”) system, maneuvering characteristics are improved by performing control in which an actuator for driving a rudder controlling mechanism is given FBW control-law commands, including attitude command control that associates the amount of maneuvering of a control stick with the amount of change in attitude of an aircraft, velocity command control that associates the amount of maneuvering of the control stick with the amount of change in velocity, and so forth.
A Partial Authority Flight Control System (hereinafter referred to as “PAFCS”) is a system that realizes the same control as this FBW system by using a mechanical maneuvering system in which the control stick and the rudder controlling mechanism are mechanically connected with a mechanical linkage and a linear actuator (SAS (stability augmentation system) actuator) for increasing stability.
With a PAFCS, because the control stick and the rudder controlling mechanism are mechanically connected, unlike the FBW system, it is not necessary to provide a redundant system for achieving high reliability in the control system. However, with the PAFCS, the operating range (authority) of an SAS actuator is restricted in order to allow maneuvering by a pilot even when an abnormality occurs in the control system.
As an example of PAFCS, Cited Literature 1 discloses a helicopter flight-control device constituted of a linking mechanism that drives a rudder controlling mechanism by mechanically transmitting the amount of maneuvering of a maneuvering unit to the rudder controlling mechanism, a flight-control-law computing unit that computes a flight-control law of the helicopter based on a maneuvering signal obtained by detecting the amount of maneuvering of the maneuvering unit and that outputs a driving signal for the rudder controlling mechanism, and a precision servo actuator unit that adds to the amount of maneuvering transmitted by the linking mechanism an amount of difference corresponding to a difference signal obtained by subtracting the maneuvering signal from the driving signal.